The lump in the back of rugby shirts is a GPS tracker, which is part of a sophisticated biometric tracking system used by coaches to track a variety of statistics about every player. The padded casing surrounds a unit that is commonly referred to as a GPS tracker, although it contains other measuring devices. The visible part is the packaging designed to protect both the electronics and the player from damage due to the usual impacts in rugby. The GPS tracker is kept in place in between the shoulder blades in something called a "Bro," which works in much the same way as a female athletes sports bra. The English rugby team has previously placed the units within a pouch in their shorts. The GPS tracker can reveal what a players average speed is, when a players intensity starts to drop, who is performing above or below their usual level, and some models even contain a heart-rate monitor sensor which can identify potential problems on the pitch. The GPS tracker is an important piece of kit, which is why players are seen these days carefully removing them before they swap shirts.